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6450 York St.
Denver, CO 80229
(303) 286-3000
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About the Metro Wastewater Reclamation District
The Metro Wastewater Reclamation District is the wastewater treatment authority for most of metropolitan Denver. It is a large, stand-alone special district formed by the Colorado legislature in 1961 to provide wastewater transmission and treatment services to member municipalities and special connectors in compliance with federal, state, and local laws.
The Metro District serves about 1.6 million people in a 615-square mile service area that includes Denver, Arvada, Aurora, Lakewood, Thornton, Westminster, and more than 45 sanitation and water and sanitation districts. (Click here for service area map.)
The Metro District treats about 140 million gallons of wastewater a day. It discharges the treated water into the South Platte River, where it makes up about 85 percent of the river as it flows northeastward from the discharge point for nine months of the year.
In 2005, the Metro District won its second consecutive Platinum Award. Platinum Awards are given for five consecutive years of 100% compliance with the numerical limits of its discharge permit. For more about this award, click here. Also in 2005, the US Environmental Protection Agency (EPA) awarded the Metro District first place nationally for plant operations and maintenance. For more about this award, click here.
The Metro District produces about 80 dry tons of biosolids—treated solids that result from cleaning wastewater—a day. Under the trade name METROGRO®, the Metro District applies most of the biosolids it produces to agricultural land in eastern Colorado. The National Biosolids Partnership certified the Metro District's Environmental Management System for Biosolids in 2005. To find out more, click here. The EPA awarded the Metro District first place nationally for its biosolids management accomplishments in 2004.
Wastewater Treatment Process
The Metro District collects about 140 million gallons of wastewater per day from neighborhood sewer lines and delivers it through 232 miles of interceptor sewers to the Metro District’s Robert W. Hite Treatment Facility in northeast Denver. About 8 to 10 hours are needed to treat the wastewater before discharging it into the South Platte River. More than 95 percent of the pollutants are removed, making the treated water suitable for agriculture, fish and aquatic life, industrial use, water supply, and recreation.
Primary treatment removes pollutants from wastewater through screening, skimming, and settling. Secondary treatment uses microorganisms to remove dissolved organic matter. The treated water is then disinfected with sodium hypochlorite to kill harmful microorganisms (pathogens). Before the effluent is discharged into the South Platte River, sodium bisulfite is added to neutralize the sodium hypochlorite.
In 1990, the Metro District began advanced treatment of about half its effluent to remove ammonia before discharging it into the River. By removing ammonia, more dissolved oxygen is available in the River, making it able to better support aquatic life. A $67 million project is now underway to enable the District’s treatment works to remove additional nitrates and ammonia. This project is expected to be completed in 2012. A $325 million project that begins in the fall of 2009 will enable the South Plant to remove ammonia and nitrates.
The Metro District removes and concentrates solids from the primary and secondary treatment processes and sends this mixture to anaerobic digesters where it is stabilized in an anaerobic digestion process. The stabilized solids, now called biosolids, can then be used as soil amendments to enrich agricultural lands. The Metro District produces about 80 dry tons of biosolids daily and applies it to both private and Metro District-owned land. Anaerobic digestion also produces methane, a renewable biogas that is used to operate a combined heat and power facility composed of gas turbines and a heat recovery hot water system. The gas turbines produce electricity, and the waste heat is used to heat the digesters and several other buildings at the Metro District’s Robert W. Hite Treatment Facility.
About 95 percent of the Metro District's biosolids are dewatered until they are about 23 percent solids (and, therefore, 77 percent water) and applied to agricultural land as a “cake.” Biosolids are also used to make compost. The nutrient- and organically rich products are marketed under the METROGRO® trade name. They help enrich Colorado's thin soils and prevent erosion. Strict federal and state regulations govern application of biosolids to Metro District and privately-owned agricultural land.
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Additional Facts
The Metro District serves 59 local governments, including both cities and sanitation districts. Of these local governments, 22 are Metro District members that have voting representation on the Metro District's Board of Directors, 25 are special connectors that have direct contracts with the Metro District, and the remaining entities are served indirectly through members and special connectors.
The chief executive officers of the member governments appoint members to the Metro District’s Board of Directors, with one director for each 75,000 population in the represented area. While special connectors are not represented on the Board, they receive the same services as members at the same cost.
The cost of transmission and treatment service is based upon the amount (flow) and strength (loadings) of the wastewater each customer puts into the Metro District's system.
The Metro District's service area encompasses about 615 square miles, including all of Denver, parts of Adams, Arapahoe, Jefferson and Douglas counties, and about 45 sanitation, water, and sanitation special districts. The Metro District’s Central Treatment Plant is the largest wastewater treatment facility in the Rocky Mountain West.
Until 1990, the Metro Wastewater Reclamation District was known as Metropolitan Denver Sewage Disposal District No. 1, the name it was given when it was formed under state law in 1961. Construction on the Robert W. Hite Treatment Facility and 50 miles of interceptor sewer lines began in 1964, and the plant began operating in 1966.
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